1. Field of the Invention
The present invention relates to an engine generator. In particular, the present invention relates to an improvement of an engine generator in which an engine and a generator coaxially connected to the engine are housed in a soundproofing case.
2. Description of the Related Art
Engine-driven generators are typically used as a power source for work performed outdoors such as, for example, on construction sites. Furthermore, many generators are completely covered with a soundproofing case so as to minimize operating noise in consideration of the operational and surrounding environments when performing work at night in an urban area. In engine generators, the number of intake and exhaust openings is decreased and the size of the intake and exhaust openings is reduced in the pursuit of achieving operational silence. However, since the overall size of the openings is small, adequate consideration to cooling the interior of the soundproofing case must be taken.
From such a viewpoint, an engine generator disclosed in Japanese Utility Model Registration Publication No. 1-3777 includes, within a soundproofing case, a duct covering an engine cylinder head and an exhaust muffler, wherein cooling air is forcibly driven into the duct by a cooling fan, thereby cooling the engine and the exhaust muffler and eliminating thermal effects on other components of the generator.
However, in the above-mentioned conventional arrangement, since outer shells of the engine and the generator are disposed so as to be exposed within the soundproofing case, there is a possibility that, depending on the positions of internal components, the heat released from the outer shells of the engine and the generator might be retained within the soundproofing case.
The present invention has been carried out in view of the above-mentioned circumstances, and it is an object of the present invention to provide an engine generator that prevents heat from being retained within a soundproofing case and has enhanced soundproofing performance.
In order to accomplish the above-mentioned object, in accordance with a first aspect of the present invention, there is proposed an engine generator that includes an engine, a generator coaxially connected to the engine, and a soundproofing case housing the engine and the generator. The soundproofing case is divided into three, that is, a chamber to be cooled, and engine-side and generator-side air intake chambers on opposite sides of the chamber to be cooled, the chamber to be cooled housing an exhaust muffler and the majority of the engine and the generator. Ventilation pathways are formed between an exhaust vent, which is provided in an upper part of the soundproofing case so as to open into the chamber to be cooled, and engine-side and generator-side outside air inlets, which are provided in the soundproofing case so as to open into the engine-side air intake chamber and the generator-side air intake chamber, so that air that is taken into the two air intake chambers from outside the soundproofing case via the corresponding outside air inlets flows from the two air intake chambers, passes through the chamber to be cooled and is discharged via the exhaust vent to the outside of the soundproofing case.
In accordance with this arrangement, sections of the engine generator that have a high temperature are placed together in the chamber to be cooled, which is in the middle, and the ventilation pathways are formed so that cooling air that flows into the chamber to be cooled from the engine-side and generator-side air intake chambers that function as cool zones flows past each part disposed in the chamber to be cooled and is smoothly discharged to the outside via the exhaust vent. Therefore, it is possible to cool the engine generator effectively while suppressing the retention of heat within the soundproofing case, and to enhance the soundproofing performance by utilizing the two air intake chambers as zones for suppressing leakage of operating noise.
In addition to the above-mentioned first aspect, in accordance with a second aspect of the present invention, there is proposed an engine generator wherein the exhaust muffler is disposed above the generator within the chamber to be cooled, and the exhaust vent is provided in the soundproofing case to discharge exhaust gas from the exhaust muffler combined with cooling air that has flowed through the ventilation pathways. In accordance with this arrangement, since the ventilation effect of natural convection within the chamber to be cooled can be utilized, the cooling efficiency can be enhanced and, moreover, since the exhaust gas from the engine is discharged outside the soundproofing case after being mixed with cooling air, the exhaust noise can be reduced.
In addition to the above-mentioned first aspect, in accordance with a third aspect of the present invention, there is proposed an engine generator further including an air cleaner and a carburetor housed in the engine-side air intake chamber, and an electrical component housed in the generator-side air intake chamber. In accordance with this arrangement, since equipment that is susceptible to heat is disposed in the air intake chambers having a low temperature on the side corresponding to the engine and the generator, the need for a special arrangement of components and measures for heat shielding can be eliminated.
In addition to the above-mentioned second or third aspect, in accordance with a fourth aspect of the present invention, there is proposed an engine generator further including a partition disposed above the exhaust muffler so as to form an exhaust chamber between the partition and the soundproofing case, the exhaust chamber forming a part of the ventilation pathways, and a pipe guiding exhaust gas from the exhaust muffler, the pipe communicating with the exhaust chamber. In accordance with this arrangement, leakage of operating noise can be suppressed by the exhaust chamber while reducing the influence of exhaust heat on the engine and the generator, thereby further enhancing the soundproofing performance.
In addition to any one of the above-mentioned first to fourth aspects, in accordance with a fifth aspect of the present invention, there is proposed an engine generator wherein the soundproofing case is divided into three, that is, the chamber to be cooled, the engine-side air intake chamber, and the generator-side air intake chamber, by means of an engine-side partition and a generator-side partition. The engine-side partition is fixedly disposed in the soundproofing case so that an engine-side inlet provided in the engine for guiding cooling air to an engine-side cooling fan of the engine faces the engine-side air intake chamber. The generator-side partition is fixedly disposed in the soundproofing case so that a generator-side inlet provided in the generator for guiding cooling air to a generator-side cooling fan of the generator faces the generator-side air intake chamber. The engine-side and generator-side outside air inlets are provided in the soundproofing case so as to provide communication between the outside and lower parts of the engine-side and generator-side air intake chambers.
In accordance with this arrangement, since a cooling air passage of the engine itself is utilized as a passage providing communication between opposite sides of the engine-side partition, and a cooling air passage of the generator itself is utilized as a passage providing communication between opposite sides of the generator-side partition, the ventilation pathways can be formed with a simple structure and, moreover, the effect of natural ventilation within the chamber to be cooled immediately after operation is stopped can be improved, thereby comparatively quickly cooling the engine and the generator after operation is stopped.
The above-mentioned object, other objects, characteristics and advantages of the present invention will become apparent from an explanation of a preferred embodiment that will be described in detail below by reference to the attached drawings.